why not if it works for you, right?

If it works for you, that's fine.

You can also subtract by adding

eg subtract 79 from 180

9 + 1 = 10

carry 1

8 + 0 = 0

0 = 1 = 1

answer: 101

If you take a Positive Number, then add a Negative Number to it, you will actually be subtracting.